Architecture for power modules such as power inverters

ABSTRACT

Power converters such as power modules configured as inverters employ modularized approaches. In some aspects, semiconductor devices are thermally coupled directly to thermally conductive substrates without intervening dielectric or insulative structures. Additionally, or alternatively, semiconductor devices are thermally coupled to thermally conductive substrates with relatively large surface areas before heat transferred from the semiconductor devices encounters a dielectric or electrically insulating structure with correspondingly high thermal impedance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure is generally related to electrical power systems, andmore specifically to power converter architectures such as power modulessuitable for rectifying, inverting and/or converting electrical powerbetween power sources and loads.

2. Description of the Related Art

Power converters are used to transform and/or condition power from oneor more power sources to supply to one or more loads. An inverter iscommonly used to transform direct current (DC) to alternating current(AC), for use in supplying power to an AC load. A rectifier is commonlyused to transform AC to DC. A DC/DC converter is commonly used to stepup or step down a DC voltage. An appropriately configured and operatedpower converter may perform any one or more of these functions. As usedherein and in the claims which follow, the term “converter” applies toall converters whether inverters, rectifiers and/or DC/DC converters.

A large variety of applications require power transformation and/orconditioning. For example, a DC power source such as a fuel cell system,battery and/or ultracapacitor may produce DC power, which must beinverted to supply power to an AC load such as a three phase AC motor inan electric or hybrid vehicle. A photovoltaic array may produce DC powerthat must be inverted to supply or export AC power to a power grid of autility. An AC power source such as a power grid or micro-turbine mayneed to be rectified to supply power to a DC load such as a tool,machine or appliance or the DC input of an inverter. A high voltage DCsource may need to be stepped down to supply a low voltage load, or alow voltage DC source may need to be stepped up to supply a high voltageload. Other applications will become apparent to those skilled in theart based on the teachings herein.

Power modules are typically self-contained units that include aconverter to transform and/or condition power from one or more powersources for supplying power to one or more loads. Power modulestypically employ transistors, diodes and other components that generatesubstantial heat during operation, particularly when operating at highloads. Excessive heat can cause the components to under perform or evenfail if not adequately addressed. Conventional power module structuresemploy various electrically insulating layers for electricallyinsulating the various components from one another and from the exteriorof the power module. For example, components are typically mounted ondirect bond copper (DBC) or direct bond aluminum (DBA) substrates, whichcomprise a ceramic substrate with metal foil fused on both sides. Theseelectrically insulating layers also tend to be thermally insulating,significantly decreasing the ability to transfer heat away from theelectronics.

Many applications for power converters are cost and/or size sensitive.These applications will employ other alternatives if sufficientlyinexpensive converters are not available in packages with a sufficientlysmall footprint. Thus, it is desirable to reduce the cost and footprintof power converters, without reducing the rated power. It is furtherdesirable to enhance the heat transfer characteristics in a powermodule, which may improve reliability and which may lower costs byreducing the amount of silicon required to accommodate the thermalcharacteristics of the power module. Further, it is desirable to be ableproduce a variety of power modules from relatively few commoncomponents, to cost effectively accommodate customers' varyingrequirements while incurring a minimal level in design costs andmaintaining a minimal level of inventory.

BRIEF SUMMARY OF THE INVENTION

Power converters such as power modules configured as inverters employmodularized approaches. In some aspects, semiconductor devices arethermally coupled directly to thermally conductive substrates withoutintervening dielectric or insulative structures. Additionally, oralternatively, semiconductor devices are thermally coupled to thermallyconductive substrates with relatively large surface areas, effectivelyspreading the heat transferred from the semiconductor devices before theheat encounters a dielectric or electrically insulating structure withcorrespondingly high thermal impedance.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not drawn to scale, and some of these elementsare arbitrarily enlarged and positioned to improve drawing legibility.Further, the particular shapes of the elements as drawn, are notintended to convey any information regarding the actual shape of theparticular elements, and have been solely selected for ease ofrecognition in the drawings.

FIG. 1 is a top, front, right isometric view of a low-side switch modulefor use in a power module according to one illustrated embodiment.

FIG. 2 is an exploded top, left, front isometric view of the low-sideswitch module of FIG. 1.

FIG. 3 is a top, front, right isometric view of a high-side switchmodule for use in a power module according to one illustratedembodiment.

FIG. 4 is an electrical schematic of a converter circuit in the form ofan inverter comprising the low-side and side-side switch modules ofFIGS. 1-3 according to one illustrated embodiment.

FIG. 5 is a partially exploded bottom, rear, left isometric view of ahalf-bridge inverter module formed from two pairs of the low- andhigh-side switches of FIGS. 1-3 according to one illustrated embodiment.

FIG. 6 is a top, front, right isometric view of the half-bridge invertermodule of FIG. 5.

FIG. 7 is a partially exploded bottom, front, left isometric view of thehalf-bridge inverter module of FIGS. 5 and 6 with a circuit boardflipped over to better illustrate first and second sets of capacitorscarried by the circuit board.

FIG. 8 is a partially exploded bottom, front, right isometric view of ahalf-bridge inverter module formed from two pairs of the low- andhigh-side switches of FIGS. 1-3, employing fasteners and conductivebridges rather than upright portions for making electrical connectionsaccording to another illustrated embodiment, with the circuit boardflipped over to better illustrate first and second sets of capacitorscarried by the circuit board.

FIG. 9 is an exploded top, front, right isometric view of a circuitboard for use in the half-bridge inverter modules of FIGS. 5-8,according to another illustrated embodiment.

FIG. 10 is a partially exploded top, front, left isometric view of athree-phase inverter formed from three of the half-bridge invertermodules of FIGS. 5-7, according to one illustrated embodiment.

FIG. 11 is a top, rear, right isometric view of the three-phase inverterof FIG. 10.

FIG. 12 is a top, right, front isometric view of a first conductive basesubstrate and associated structures suitable for use in a low-sideswitch module and a second conductive base substrate and associatedstructures suitable for use in a high-side switch module, according toone illustrated embodiment.

FIG. 13 is a top, right, front isometric view of a low-side switchmodule employing the first conductive base substrate of FIG. 12,according to one illustrated embodiment.

FIG. 14 is a top, right, front isometric view of a high-side switchmodule employing the second conductive base substrate of FIG. 12,according to one illustrated embodiment.

FIG. 15 is a top, right, front isometric view of a half-bridge modulecomprising a phase bar and two pairs of the low- and high-side switchmodules of FIGS. 13 and 14, according to one illustrated embodiment.

FIG. 16 is a top, right, front isometric view of a half-bridge modulecomprising a phase bar and two pairs of the low- and high-side switchmodules similar to those of FIGS. 13 and 14, according to anotherillustrated embodiment.

FIG. 17 is a top, rear, right isometric view of a switch module suitablefor use as both a low- and high-side switch, according to oneillustrated embodiment.

FIG. 18 is a top, front, right isometric view of a half-bridge moduleformed form two of the switch modules of FIG. 17, according to oneillustrated embodiment.

FIG. 19 is a top, front, right isometric view of a single phasehalf-bridge inverter formed by the half-bridge module of FIG. 18,according to one illustrated embodiment.

FIG. 20 is a top, front, left isometric view of a half-bridge module,according to one illustrated embodiment, where a single housing receivestwo switch modules.

FIG. 21 is a top, rear, left isometric view of the half-bridge module ofFIG. 20.

FIG. 22 is a partially broken top, left, rear, isometric view of thehalf-bridge module of FIGS. 20 and 21.

FIG. 23 is an electrical schematic diagram of a circuit formed by thehalf-bridge modules of FIGS. 20-22

FIG. 24 is a top, front, left isometric view of a three-phase inverterformed by three of the half-bridge module of FIGS. 20-21.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of theinvention. However, one skilled in the art will understand that theinvention may be practiced without these details. In other instances,well-known structures associated with power converters, such as controlsystems including microprocessors and drive circuitry have not beenshown or described in detail to avoid unnecessarily obscuringdescriptions of the embodiments of the invention.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment. Furthermore, the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

The headings provided herein are for convenience only and do notinterpret the scope or meaning of the claimed invention.

FIGS. 1 and 2 show a low-side switch module 10 suitable, for example,for use in a low-side of a modularized converter circuit of a powermodule, such as a DC→AC inverter. The low-side switch module 10comprises a conductive base plate 12, an electrically insulative housing14, a conductive member 16, a number of semiconductor devices 18 and acontrol resistor board 20.

The base plate 12 is preferably a solid slab of conductive material,such as copper or aluminum, without any electrically or thermallyinsulative material. The housing 14 is an insulative material such as aplastic, epoxy and/or epoxy impregnated fiber glass. The housing 14 maybe formed using a variety of techniques, for example, via injectionmolding. The housing 14 may be mechanically coupled to the base plate 12using fasteners received through holes or apertures provided in thehousing 14 and base plate 12, and/or adhesive. The housing 14 forms anopening 22, exposing a portion of the base plate 12.

The conductive member 16 may be insert molded in the housing 14 tosecure the conductive member 16 therein, and to electrically insulatethe conductive member 16 from the base plate 12. A perimeter portion 24of the conductive member 16 extends from at least a portion of aperimeter of the opening 22 of the housing 14, exposing a portion of theconductive member 16 within the opening 22 of the housing 14 for makingelectrical connections thereto as discussed in detail below. An uprightportion 26 of the conductive member 16 extends from the housing 14 at anapproximately right angle to the base plate 12.

The semiconductor devices 18 are carried by the base plate 12, andpositioned thereon so as to be exposed by the opening 22 of the housing14. The semiconductor devices 18 may take the form of transistors and/ordiodes, such as metal oxide semiconductor field effect transistors(MOSFETs) and/or insulated gate bipolar transistors (IGBTs). Suchtransistors are commercially available, individually, or in sets of twoor six transistor switches. The transistors typically include theanti-parallel diodes which may or may not be an inherent portion of thefabricated semiconductor transistor structure. The transistors areessentially three element devices, comprising a pair of active elements(e.g., source/emitter, drain/collector) and a control element, (e.g.,gate, base). While only one of the terms (e.g., source rather than drainor source/drain) are occasionally used henceforth, those of skill in theart will recognize that such is for convenience only, and such use doesnot restrict the teachings or claims to MOSFETs, but are also applicableto other types of transistors, for example, IGBTs.

The semiconductor devices 18 are preferably unpackaged or bare dice. Oneactive terminal (e.g., drain, collector) of each of the semiconductordevices 18 may be electrically and thermally coupled to the base plate12 by surface mounting. The other active terminal (e.g., source,emitter) of each of the semiconductor devices 18 may be electricallycoupled to the perimeter portion 24 of the conductive member 16 via oneor more wire bonds 28 (only one illustrated for clarity ofpresentation). Thus, the semiconductor devices 18 are electricallycoupled in parallel, and may be operated in parallel, receiving the sameswitching signals at approximately the same time, as discussed below.

The control resistor board 20 includes a terminal block 30 withterminals 32 for receiving control signals (e.g., gate drive signals)from a controller (e.g., gate drive board) (not shown). The controlresistor board 20 also includes a plurality of resistors 34 andconductive traces (not shown). The control resistor board 20 iselectrically coupled to the control terminals (e.g., gates, bases) ofthe semiconductor devices 18 via wire bonds 36 (only one shown).

FIG. 3 shows a high-side switch module 40 according to one illustratedembodiment. The high-side switch module 40 is substantially similar tothe previously described low-side switch module 10, thus commonstructures are identified by the same reference numbers. Onlysignificant differences in structure and operation are described below.

In particular, the high-side switch module 40 includes an uprightportion 42 that extends from, and is electrically coupled to the baseplate 12. This contrasts with the upright portion 26 of the low-sideswitch module 10, which extends from and is electrically coupled to theconductive member 16.

FIG. 4 shows a half-bridge circuit 44 that may be formed by electricallycoupling the low-side switch module 10 and high-side switch module 40,according to one illustrated embodiment. The semiconductor devices 18 ofthe switch modules 10, 40 forming the half-bridge circuit 44 may beoperated to, for example, invert DC power from a DC source such as afuel cell stack, battery and/or ultracapacitor to AC power to drive anAC load such as a thee phase electric motor.

In particular, the conductive member 16, or upright portion 26 thereof,of the low-side switch module 10 (FIG. 1) is electrically coupled to anegative side of a DC supply, for example, via a negative rail or plate46 of a DC bus. The base plate 12, or upright portion 42 thereof, of thehigh-side switch module 40 (FIG. 3) is electrically coupled to apositive side of the DC supply, for example, via a positive rail orplate 48 of the DC bus. An AC output appears on the base plate 12 of thelow-side switch module 10 and on the conductive member 16 of thehigh-side switch module 40, which may be electrically shorted together.

FIGS. 5-7 show two pairs of low- and high-side switch modules 10, 40coupled to form a half-bridge inverter module 50. In particular, acircuit board 52 carries a first pair of low- and high-side switches 10a, 40 a mounted proximate each other and electrically coupled togetheras a half-bridge circuit 44 (FIG. 4), and a second pair of low-side andhigh-side switches 10 b, 40 b also mounted proximate each other andelectrically coupled together as a half-bridge circuit 44 (FIG. 4). Inthis embodiment, the terminals formed at the distal end of the uprightportions 26, 42 are received in through-holes formed in the circuitboard 52 and manually soldered thereto. The circuit board 52 istypically a lamination of electrically conductive and electricallyinsulative layers, which may carry a number of electrically conductivetraces. Often, the circuit board 52 will include at least one heavycopper layer in order to carry the high currents typically encounteredin most power inverter applications.

The circuit board 52 may carry a first number of bus capacitors 54 aelectrically coupled to the first pair of switch modules 10 a, 40 a anda second set of bus capacitors 54 b electrically coupled to the secondpair of switch modules 10 b, 40 b. The bus capacitors 54 a, 54 b mayreduce or eliminate voltage overshoot. The half-bridge inverter module50 may also include one or more bridges, shown and discussed in detailbelow with reference to FIG. 8.

The base plates 12 may be thermally coupled to one or more pluralitiesof heat exchange members, with or without, any intervening thermallyinsulative structures. Such as structure is taught in commonly assignedU.S. application Ser. No. 10/738,926, filed Dec. 16, 2003 and entitled“POWER MODULE WITH HEAT EXCHANGE” (Express Mail No. EV336618969US), andincorporated herein in its entirety. Thermally coupling without anyintervening thermally insulative structures has distinct advantages formaximizing the effectiveness of heat removal, and thereby improvingreliability and possibly allowing the use of less silicon (e.g., fewersemiconductor devices to handle a given power) and hence reducing thecost of the units. In some embodiments, the switch modules 10, 40 may beenclosed in a module housing to provide electrical and/or environmentalisolation. While the module housing may primarily be electricallyinsulative, and hence thermally insulative, the illustrated embodimentadvantageously increases the surface area of the heat sink (e.g., baseplates 12) before heat transported from the semiconductor devices 18encounters a first interface (e.g., connection between base plates 12and the module housing) with an electrically and/or thermally insulativelayer or structure (e.g., module housing).

FIG. 8 shows another embodiment of the half-bridge inverter module 50,employing fasteners such as screw-down terminals for making physicaland/or electrical connections between the switch modules 10, 40 and thecircuit board 52, rather than soldering as illustrated in FIGS. 5-7.This permits the use of wave soldering with the switch modules 10, 40,since the circuit board 52 can now be easily attached to the switchmodules 10, 40 using the fasteners after wave soldering. This alsoallows the configuration to be decided upon immediately before assembly,allowing last minute customization.

In particular, the low- and high-side switch modules 10, 40 omit theupright structures 26, 42, respectively, of the previous embodiments. Arespective conductive bridge 56 electrically couples the base plate 12of each of the switch modules 10 a, 10 b, 40 a, 40 b to the circuitboard 52. The conductive bridge 56 may be generally U-shaped, with thelegs of the U-shape sized and spaced to be accommodated by a couplingstructure 58 formed in the housing 14. The conductive bridge 56 may takea variety of other shapes, for example, trapezoidal, where suitable forthe particular shape of the housing 14 and base plate 12. Fasteners 60,for example screws or bolts, may be received through holes 62, 64, 66,67 formed in the circuit board 52, conductive bridges 56, housings 14and base plates 12, respectively, for securing the physical and/orelectrical connections therebetween.

FIG. 9 shows a circuit board 68 according to another illustratedembodiment, suitable for use with the half-bridge inverter module 50 ofFIG. 8. For example, the circuit board 68 may be suitable for carryingthe bus capacitors 54 a, 54 b, and electrically coupling the buscapacitors 54 a, 54 b and the low- and high-side switch modules 10 a, 10b, 40 a, 40 b. In particular, the circuit board 68 comprises anelectrically insulating layer 70 laminated between two conductive layers72, 74. The conductive layers 72, 74 may be precut to a desired pattern.The conductive layers 72, 74 may be relatively thin, for example made ofcopper or aluminum foil. The circuit board 68 may replace the heavycopper circuit board 52 discussed above in reference to FIGS. 5-8,significantly reducing material costs and/or inductance.

FIGS. 10 and 11 show a three-phase inverter 80 formed from three of thehalf-bridge inverter modules 50 described above with reference to FIGS.5-7 and/or FIG. 8 and denominated 50 a-50 c. The three-phase inverter 80comprises a mounting plate 82, and six electrically nonconductiveisolation pads 84 a-84 f carried on a surface of the mounting plate 82.The mounting plate 82 may be formed from a conductive material, forexample, copper or aluminum. The isolation pads 84 a-84 f may take theform of a variety of electrically insulating materials, although thosewith a low thermal impedance may be preferred. For example, a suitablematerial for the isolation pads 84 a-84 f may be ISOSTRATE™, a polymidefilm with a phase change material on each opposed surface of the film toprovide a high dielectric effect with a low thermal impedance, which iscommercially available from Power Devices Inc. of Laguna Hills, Calif.Each isolation pad 84 a-84 f carries a pair of low- and high-side switchmodules 10, 40.

While the isolation pads 84 a-84 f may be electrically insulative, andhence to some extent thermally insulative, the illustrated embodimentadvantageously increases the surface area of the heat sink (e.g., baseplates 12) before heat transported from the semiconductor devices 18encounters a first interface (e.g., connection between base plates 12and isolation pads 84 a-84 f) with an insulative (electrically and/orthermally) layer or structure (e.g., isolation pads 84 a-84 f). Thisapproach enhances the ability to transport heat away from thesemiconductor devices, increasing reliability and potentially reducingthe amount of silicon required, and hence the cost.

Each of the half-bridge inverter modules 50 a-50 c of the three-phaseinverter 80 comprises a respective one of the circuit boards 52, 68previously discussed and denominated 52 a-52 c. Each of the half-bridgeinverter modules 50 a-50 c of the three-phase inverter 80 comprises arespective phase terminal 86 a-86 c. The phase terminals 86 a-86 c maytake the form of elongated conductors for example, elongated copperplates, bands or bars, with or without appropriate cutouts and folds orbends to accommodate the structure of the housings 14 of the switchmodules 10, 40. The phase terminals 86 a-86 c may additionally oralternatively include a folded over portion to provide structuralstrength and/or to form an attachment structure for making externalconnections thereto. A portion, for example the folded over portion, mayextend out of the housing 14 to facilitate external connections. Thephase terminals 86 a-86 c may be soldered or otherwise fastened to thephase outputs of the low- and high-side switch modules 10, 40,respectively. For example, the phase terminals 86 a-86 c areelectrically coupled to the base plate 12 of each of the low-side switchmodules 10 and to the conductive member 16 of each of the high-sideswitch modules 40. The phase terminals 86 a-86 c and circuit boards 52a-52 c may include aligned holes for receiving screws for mounting thephase terminals 86 a-86 c to the phase outputs of the low- and high-sideswitch modules 10, 40.

The three-phase inverter 80 may further comprise a pair of DC terminals88 a, 88 b. The DC terminals 88 a, 88 b are commonly referred to as busbars, but can take any variety of shapes and sizes. A dielectric may bereceived between the DC terminals 88 a, 88 b, to electrically isolatethe DC terminals 88 a, 88 b from one another, and reduce or eliminateinductance. Some DC terminal structures are discussed in commonlyassigned U.S. application Ser. No. 09/882,708, filed Jun. 15, 2001; U.S.application Ser. No. 09/957,568, filed Sep. 20, 2001; U.S. applicationSer. No. 10/109,555, filed Mar. 27, 2002; and U.S. application Ser. No.60/471,387, filed May 16, 2003. The DC terminals 88 a, 88 b may extendperpendicularly to the phase terminals 86 a-86 c, and may comprisecutouts 90 for accommodating the phase terminals 86 a-86 c withoutmaking electrical contact therewith. The DC terminals 88 a, 88 b may besoldered or otherwise fastened (e.g., screwed or bolted) to the DCinputs of the low- and high-side switch modules 10, 40. For example, anegative one of the DC terminals 88 a, 88 b may be coupled to theconductive member 16 of the low-side switch modules 10 via the circuitboards 52 a-52 c, and a positive one of the DC terminals 88 a, 88 b maybe coupled to the base plate 12 or upright portion 26 of the high-sideswitch modules 40 via the circuit boards 52 a-52 c.

FIG. 12 shows a number of semiconductor devices 18 provided asunpackaged or bare dice each having an active terminal (e.g., collector,drain) electrically and thermally coupled to a surface 100 of aconductive base substrate 102 by surface mounting. The surface 100 ofthe conductive base substrate 102 also carries an insulative substrate104. The insulative substrate 104 carries one or more conductivepatterns 106 a, 106 b for routing control signals (e.g., gate drivesignals) to the control terminals (e.g., gates, bases) of thesemiconductor devices 18. The conductive base substrate 102 andassociated structure are particularly suitable for use in a low-sideswitch module, as discussed in detail below.

FIG. 12 also shows a conductive base substrate 110. A surface 111 of theconductive base substrate 110 carries an insulative substrate 112. Theinsulative substrate 112 carries a conductive secondary substrate 114.The conductive secondary substrate 114 may, for example, take the formof a DBC substrate. The conductive secondary substrate 114 carries anumber of semiconductor devices 18, provided as unpackaged or bare diceeach having an active terminal (e.g., collector, drain) electrically andthermally coupled to the conductive secondary substrate 114 via surfacemounting techniques. The insulative substrate 112 also carries one ormore conductive patterns 116 a, 116 b for routing control signals (e.g.,gate drive signals) to the control terminals (e.g., gates, bases) of thesemiconductor devices 18. The conductive base substrate 110 andassociated structure are particularly suitable for use in a high-sideswitch module, as discussed in detail below.

While the insulative substrate 112 may be electrically insulative, andhence to some extent thermally insulative, the illustrated embodimentadvantageously increases the surface area of the heat sink (e.g.,conductive base substrate 110) before heat transported from thesemiconductor devices 18 encounters a first interface (e.g., connectionbetween conductive base substrate 110 and insulative substrate 112) withan insulative (electrically and/or thermally) layer or structure (e.g.,insulative substrate 112). This enhances the ability to transport heataway from the semiconductor devices, increasing reliability andpotentially reducing the amount of silicon required, and hence the cost.

FIG. 13 shows a low-side switch module 10 according to one illustratedembodiment, employing the conductive base substrate 102 and associatedstructure of FIG. 12. As in the previous embodiments, the low-sideswitch module 10 includes a housing 14 forming an opening 22. Aconductive member 16 is insert molded with the housing 14 and has afirst portion 118 extending externally from the housing 14 and another(i.e., perimeter) portion 24 extending internally into the opening 22.The first portion 118 is bent or folded back on itself to extend spacedfrom and along a portion of the housing 14. The exposed (i.e., die sideup) active terminals (e.g., source, emitter) of the semiconductordevices 18 are electrically coupled to the perimeter portion 24 of theconductive member 16 extending into the opening 22 via one or more wirebonds 119 a (only one illustrated), for electrical coupling to anegative DC source, for example via a negative DC bus, discussed below).As discussed above, other active terminals (e.g., drain, collector) ofthe semiconductor devices 18 are surface mounted to the conductive basesubstrate 102 to electrically couple that active terminal to a phaseoutput (illustrated in FIG. 15 and discussed below). The low-side switchmodule 10 may also include a number of gate pins or terminals 120 insertmolded with the housing 14, and extending upward from the housing 14 formaking external connections to a controller (not shown).

FIG. 14 shows a high-side switch module 40 according to one illustratedembodiment, employing the conductive base substrate 110 and associatedstructure of FIG. 12. As in the previous embodiments, the high-sideswitch module 40 includes a housing 14 forming an opening 22. Aconductive member 16 is insert molded with the housing 14 and has afirst portion 118 extending externally from the housing 14 and another(i.e., perimeter) portion 24 extending internally into the opening 22.The first portion 118 is bent or folded back on itself to extend spacedfrom and along a portion of the housing 14. The exposed (die side up)active terminals (e.g., source, emitter) of the semiconductor devices 18are electrically coupled to the conductive base substrate 110 via one ormore wire bonds 119 b (only one illustrated), for electrically couplingthe active terminal (e.g., source, emitter) of the semiconductor device18 to a phase output (illustrated in FIG. 15 and discussed below). Theconductive secondary substrate 114, to which semiconductor devices 18are surface mounted, is electrically coupled to the perimeter portion 24of the conductive member 16 extending into the opening 22 by one or morewire bonds 119 c (only one illustrated), for electrically coupling theother active terminal (e.g., drain, collector) to a positive DC source,for example via a positive DC bus, discussed below. The high-side switchmodule 40 may also include a number of gate pins or terminals 120 insertmolded with the housing 14, and extending upward from the housing 14 formaking external connections to a controller (not shown).

FIG. 15 shows a half-bridge structure 122 according to one embodiment,formed using the low- and high-side switch modules 10, 40 of FIGS.12-14. The half-bridge structure 122 comprises a phase bar 124 to whichthe conductive base substrates 102, 110 of pairs of low- and high-sideswitch modules 10 a, 40 a, 10 b, 40 b are physically and electricallycoupled using solder or appropriate fasteners such as screws, bolts, orclamps (not shown) received through holes 126 formed in the conductivebase substrates 102, 110. The phase bar 124 may be formed from a varietyof conductive materials, for example, copper or aluminum, and may beformed by extrusion, molding, stamping or other suitable manufacturingoperations. The first portion 118 of the conductive members 16 extendingexternally from the housing 14 of the pairs of low and high-side switchmodules 10 a, 40 a, 10 b, 40 b folds over the phase bar 124 (illustratedby broken lines, and arrow 123), and is spaced from the phase bar 124,forming terminals for making electrical connections to the DC supply,for example via a DC bus.

FIG. 16 shows a half-bridge structure 122 according to anotherembodiment, employing switch modules 10, 40 similar to those of FIGS.12-14. In this embodiment, the first portion 118 of the conductivemembers 16 extending externally from the housing 14 of each of the low-and high-side switch modules 10 a, 40 a, 10 b, 40 b are folded backtoward, but not over, the phase bar 124, and include coupling structuressuch as holes 128, which may or may not may be threaded, for makingelectrical connections to the DC supply, for example via a DC bus.

FIG. 17 shows a switch module 130 capable of use as both low-side andhigh-side switches. A number of the elements are identical or similar tothose in previously described embodiments, so are designated with thesame reference numerals as in those previously described embodiments.Only significant differences in structure are discussed below.

The switch module 130 comprises a conductive base plate 12 and anelectrically insulative housing 14 coupled to the base plate 12 by wayof adhesive and/or fasteners. The switch module 130 also includes aconductive member 16, insert molded in the housing 14. The conductivemember 16 comprises a perimeter portion 24 extending internally from thehousing into an opening 22 formed by the housing 14, and a portionextending externally from the housing 14 to which the lead line from thereference numeral 16 points.

The switch module 130 also comprises a number of semiconductor devices18, preferably provided as unpackaged or bare dice. Each ofsemiconductor devices 18 comprises at least one active terminal (e.g.,drain, collector) electrically and thermally coupled to the base plate12, for example, via surface mounting techniques. The other activeterminal (e.g., source, emitter) is electrically coupled to theperimeter portion 24 of the conductive member 16 via one or more wirebonds 28 (only one illustrated in FIG. 18).

The base plate 12 carries an insulative substrate 104, which in turncarries one or more conductive patterns 106 a-106 c for routing controlsignals (e.g., gate drive signals) to the control terminals of thesemiconductor devices 18 from a controller (not shown). In particular,the control signals may be received at a set of gate pins or terminals120, insert molded in the housing 14. The gate pins or terminals 120 mayextend into the opening 22 of the housing 14, and may be electricallycoupled to the conductive patterns 106 a-106 c via wire bonds 36 (onlyone illustrated in FIG. 18). The conductive patterns 106 a-106 c areelectrically coupled to the control terminals of the semiconductordevices 18, for example via one or more wire bonds (not illustrated inFIG. 18). The insulative substrate 104 may comprise one or more layers,where at least one layer is electrically insulative. For example, theinsulative substrate 104 may take the form of a DBC substrate.

The switch module 130 further comprises one or more power posts 132 a,132 b electrically coupled to, and extending from, the base plate 12 formaking electrically connections thereto. As will be explained in detailbelow, the power posts 132 a, 132 b and conductive member 16 serve asthe terminals for making electrical connections to the positive andnegative poles of the DC supply or bus, and for making electricalconnections to the phase output to the AC load. The ability to switchthe functions of the power posts 132 a, 132 b and conductive member 16,allows a single switch module 130 to be used for both low-side andhigh-side switching, reducing costs associated with design, manufacture,inventory, and distribution.

FIG. 18 illustrates a half-bridge module 134 formed from two of theswitch modules 130 of FIG. 17, a first switch module 130 a that willserve as the low-side switch module, and a second switch module 130 bthat will serve as the high-side switch module. In particular, theswitch modules 130 a, 130 b are oriented at 180 degrees with respect toone another to simplify electrical connections, although suchorientation is not necessary. The power posts 132 a, 132 b of the secondswitch module 130 b (i.e., high-side switch) are electrically coupled tothe positive pole of the DC supply or bus. The conductive member 16 ofthe first switch module 130 a (i.e., low-side switch) is electricallycoupled to the negative pole of the DC supply or bus. The power posts132 a, 132 b of the first switch module 130 a (i.e., low-side switch)and the conductive terminal 16 of the second switch module 130 b (i.e.,high-side switch) each provide the AC phase output.

FIG. 19 shows a single phase half-bridge inverter 136 formed by thehalf-bridge module 134 of FIG. 18. A conductive phase terminal 138electrically couples power posts 132 a, 132 b of the first switch module130 a (i.e., low-side switch) and the conductive terminal 16 of thesecond switch module 130 b (i.e., high-side switch) to provide the ACphase output. The single phase half-bridge inverter 136 may include asub-controller, such as a gate drive board 140. The gate drive board 140may be mounted across the low- and high-side switch modules 130 a, 130b. The gate pins 120 may be electrically coupled to the gate drive board140. For example, gate pins 120 may be received in throughholes formedin the gate drive board 140, and electrically coupled thereto via asolder reflow process. The gate drive board 140 may include a connector142 to couple to a controller or control board (not shown).

FIGS. 20-22 show a half-bridge inverter module 150 formed by first andsecond switch modules 152 a, 152 b according to another illustratedembodiment. In contrast to previous embodiments, the half bridgeinverter module 150 comprises a single housing 14 that receives firstand second switch modules 152 a, 152 b. The housing 14 comprises a skirtor rib that at least partially extends between the base plates 12 a, 12b of the switch modules 152 a, 152 b, respectively. An active terminal(e.g., drain, collector) of each of a first set of semiconductor devices18 a (only a few called out in the Figures) is electrically andthermally coupled to the base plate 12 a, for example via surfacemounting techniques. Likewise, an active terminal (e.g., drain,collector) of each of a second set of semiconductor devices 18 b iselectrically and thermally coupled to the base plate 12 b, for examplevia surface mounting techniques.

The housing 14 supports a first conductive member 16 a and a secondconductive member 16 b, for electrically coupling to the positive andnegative poles, respectively, of the DC supply or bus (not shown). Theconductive members 16 a, 16 b may take a variety of forms, for example,copper or aluminum bars or strips, and may be formed by stamping,extrusion, rolling, molding or other various manufacturing operations.The first and second conductive members 16 a, 16 b may be electricallyisolated from one another by an insulative member (not illustrated),such as Nomex™.

The positive conductive member 16 a is electrically coupled to the baseplate 12 a via one or more wire bonds 154 a (only two illustrated, FIG.21) to electrically couple one active terminal (e.g., drain, collector)of the semiconductor devices 18 a to the positive pole of the DC supplyor bus. The other active terminal (e.g., source, emitter) of each of thesemiconductor devices 18 a is electrically coupled to a conductiveinterconnect 156 via one or more wire bonds 154 b (only two illustrated,FIG. 21). The conductive interconnect 156 may be formed from any of avariety of conductive materials, for example, copper or aluminum. Theconductive interconnect 156 is electrically coupled to one activeterminal (e.g., drain, collector) of the semiconductor devices 12 b viathe base plate 12 b and one or more wire bonds 154 c (only twoillustrated, FIG. 21). The other active terminal (e.g., source, emitter)of each of the semiconductor devices 12 b is electrically coupled to thesecond conductive member 16 b via one or more wire bonds 154 d (only twoillustrated, FIG. 21). A phase terminal 158 is electrically coupled tothe base plate 12 b to provide the AC phase output. The phase terminal158 may comprise a coupling structure to facilitate electricalconnections to AC loads (not shown). The above described electricalcoupling forms a half-bridge circuit 160, which is schematicallyillustrated in FIG. 23.

Returning to FIGS. 20-22, a control board 162 is physically coupled tothe housing 14, and comprises a connector 164 for connecting to acontroller (not shown) to receive control signals therefrom for drivingthe semiconductor devices 18 a, 18 b. Sets of control pins 166, insertmolded in the housing 14, couple signals from the control board 162 tothe via one or more wire bonds 154 e (only one illustrated, FIG. 21).Insulating substrates 168 a, 168 b carried by the base plates 12 a, 12b, carry conductive patterns (not shown in these Figures) toelectrically coupled the control signals to the control terminals (e.g.,gate, base) of the semiconductor devices 18 via one or more wire bonds154 f (only one illustrated, FIG. 21).

The control board 162 may comprises various discrete and/or integratedor solid state electrical and electronic components. For example, thecontrol board 162 may comprise a microprocessor, application specificintegrated circuit (ASIC), or digital signal processor (DSP) configuredand/or programmed to produce gate drive signals to selectively activatethe semiconductor devices 18 a, 18 b to invert a DC supply current intoan AC output current. The control board 162 may include various sensors,for example, current sensor(s), temperature sensor(s), and/or voltagesensor(s) for detecting 1) magnitude of the input current; themagnitude, frequency and phase of the output current; and/or temperatureof various semiconductor devices 18 a, 18 b, substrates, or ambientenvironments. Further, the control systems may be configured to use thevarious measurements to control the operation of the half-bridgeinverter module 150, for example, controlling the speed, duration ororder of switching signals supplied to the semiconductor devices 18 a,18 b, or to shut down the half-bridge inverter module 150 uponoccurrence or absence of certain conditions.

FIG. 24 shows a three-phase inverter 170 comprising three of thehalf-bridge inverter modules of FIGS. 20-22, denominated 150 a-150 c.The base plates 12 a-12 c of the inverter modules 150 a-150 c arecarried by a support member 172. The inverter modules 150 a-150 c may besecured to the support member 172 using fasteners, for example, screws,bolts or clamps.

The support member 172 is preferable thermally conductive, and may, forexample, take the form of a cooling header. The cooling header mayinclude one or more heat exchange loops comprising, for example, a heattransfer medium which may take a variety of forms of fluid, for example,a liquid, gas, or a fluid that changes phase as the fluid circulatesthrough different portions of the heat exchange loop. The gas may, forexample, take the form of air. The circulation may be passive or active,for example relying on a pump, compressor or fan (not shown) to activelycirculate the heat transfer medium.

Where the support member 172 is thermally conductive it may also beelectrically conductive. In such situations, an isolation pad (not shownin FIG. 23) underlies each of the inverter modules 150 a-150 c toprevent shorting between the phase outputs of the inverter modules 150a-150 c. While the isolation pads may be somewhat thermally insulative,the illustrated embodiment advantageously increases the surface area ofthe heat sink (e.g., base plates 12 a-12 c) before heat transported fromthe semiconductor devices 18 encounters a first interface (e.g.,connection between base plates 12 a-12 c and isolation pads) with anelectrically and/or thermally insulative layer or structure (e.g.,isolation pads).

Each of the inverter modules 150 a-150 c may be physically andelectrically coupled to a respective circuit board 174 a-174 c, carryinga set of capacitors 176 a-176 c for reducing inductance.

The three-phase inverter 170 provides a compact design capable ofhandling substantial loads, while benefiting from modularization (e.g.,reduced costs associated with design, manufacture, and distribution),and while providing enhanced reliability associated with good thermalmanagement.

Although specific embodiments of and examples for the switch modules,converters and inverters and methods of manufacturing and operating thesame are described herein for illustrative purposes, various equivalentmodifications can be made without departing from the spirit and scope ofthe invention, as will be recognized by those skilled in the relevantart. The teachings provided herein of the invention can be applied toother converters and power modules, not necessarily the exemplaryinverter power module generally described above.

While elements may be described herein and in the claims as “positive”or “negative” such denomination is relative and not absolute. Thus, anelement described as “positive” is shaped, positioned and/orelectrically coupled to be at a higher relative potential than elementsdescribed as “negative” when the element is coupled to a power source.“Positive” elements are typically intended to be coupled to a positiveterminal of a power source, while “negative” elements are intended to becoupled to a negative terminal or ground of the power source. Generally,“positive” elements are located or coupled to the high-side of the powermodule and “negative” elements are located or coupled to the low-side ofthe power module.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, including butnot limited to: Ser. Nos. 60/233,992; 60/233,993; 60/233,994; 60/233,995and 60/233,996, each filed Sep. 20, 2000; Ser. Nos. 09/882,708 and09/957,047, both filed Jun. 15, 2001; Ser. Nos. 09/957,568 and09/957,001, both filed Sep. 20, 2001; Ser. No. 10/109,555, filed Mar.27, 2002; Ser. No. 60/471,387, filed May 16, 2003; and Ser. No.10/738,926, filed Dec. 16, 2003, and entitled “POWER MODULE WITH HEATEXCHANGE” (Express Mail No. EV336618969US), are incorporated herein byreference, in their entirety. Aspects of the invention can be modified,if necessary, to employ systems, circuits and concepts of the variouspatents, applications and publications to provide yet furtherembodiments of the invention.

These and other changes can be made to the invention in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the invention to thespecific embodiments disclosed in the specification and the claims, butshould be construed to include all power converters and/or power modulesin accordance with the claims. Accordingly, the invention is not limitedby the disclosure, but instead its scope is to be determined entirely bythe following claims.

1. A power converter, comprising: a phase terminal structure having atleast a first pair of opposed sides; and at least two switch modules,each of the switch modules comprising conductive base plates adjacentand electrically coupled to respective ones of the pair of opposed sidesof the phase terminal structure, each of the switch modules furthercomprising a housing forming an interior compartment, and a number ofsemiconductor switches received in respective ones of the interiorcompartments, the semiconductor switches electrically coupled torespective ones of the conductive base plates and operable to transformpower.
 2. The power converter of claim 1 wherein the semiconductorswitches of a first one of the switch modules comprise a first activeterminal, a second active terminal, and a control terminal, the firstactive terminal surface mounted to the conductive base plate; andwherein the semiconductor switches of a second one of the switch modulescomprise a first active terminal, a second active terminal, and acontrol terminal, the second active terminal electrically coupled to theconductive base plate via a number of wire bonds.
 3. The power converterof claim 2 wherein the second one of the switch modules furthercomprises an insulating substrate carried by the conductive base plateand a first conductive pattern carried by the insulating substrate, thefirst active terminal of the semiconductor switches of the second one ofthe switch modules surface mounted to the first conductive pattern. 4.The power converter of claim 3 wherein the second one of the switchmodules further comprises: a conductive member supported by the housing,the conductive member comprising a portion extending externally from thehousing and a portion extending internally in the housing; and a numberof wire bonds electrically coupling the first conductive pattern to theportion of the conductive member extending internally in the housing. 5.The power converter of claim 4 wherein the second one of the switchmodules further comprises: a set of control pins carried by the housing,a portion of the control pins extending externally from the housing anda portion of the control pins extending internally in the housing; asecond conductive pattern carried by the insulating substrate, and a setof wire bonds electrically coupling the control pins of the second ofthe switch modules to the second conductive pattern; and a set of wirebonds electrically coupling the second conductive pattern to the controlterminals of each of the semiconductor switches of the second one of theswitch modules.
 6. The power converter of claim 3 wherein the first oneof the switch modules further comprises: a set of control pins carriedby the housing, a portion of the control pins extending externally fromthe housing and a portion of the control pins extending internally inthe housing; an insulating substrate carried by the conductive baseplate and a first conductive pattern carried by the insulatingsubstrate, a set of wire bonds electrically coupling the control pins ofthe first one of the switch modules to the conductive pattern; and a setof wire bonds electrically coupling the conductive pattern to thecontrol terminals of each of the semiconductor switches of the first oneof the switch modules.
 7. The power converter of claim 6 wherein thefirst one of the switch modules further comprises: a conductive membersupported by the housing, the conductive member comprising a portionextending externally from the housing and a portion extending internallyin the housing; and a number of wire bonds electrically coupling thesecond active terminal of the semiconductor switches of the first one ofthe switch modules to the portion of the conductive member extendinginternally in the housing.
 8. The power converter of claim 3 wherein thephase terminal structure comprises a metal bar, the first one of theswitch modules mounted to a first one of the pair of opposed sides, thesecond one of the switch modules mounted to a second one of the pair ofopposed sides, and wherein each of the switch modules further comprisesa conductive member comprising an exterior portion extending externallyfrom the housing including a distal portion that extends at anapproximately right angle to the pair of opposed sides.
 9. A powerconverter, comprising: at least first switch module comprising: a firsthousing of an electrically insulative material forming an interior andan exterior, the interior of the first housing open to the exterior at afirst end and at a second end; a first conductive member supported bythe first housing, the first conductive member comprising an exteriorportion extending from the first housing into the exterior and aperimeter portion forming at least one shelf extending from the firsthousing into the interior of the first housing; a first conductive baseplate comprising a first surface and a second surface opposed to thefirst surface; a first insulating substrate carried by the first surfaceof the first conductive base plate; a conductive pattern carried by thefirst insulating substrate, the first insulating substrate electricallyinsulating the conductive pattern from the first conductive base plate;a first number of semiconductor switches each comprising a first activeterminal, a second active terminal and a control terminal, the firstactive terminal of each of the first number of semiconductor switchessurface mounted to the first surface of the first conductive base plate;a number of wire bonds electrically coupling the second active terminalof each of the first number of semiconductor switches to the shelf ofthe first conductive member; and a number of wire bonds electricallycoupling the control terminals of the first number of semiconductorswitches to the conductive pattern, wherein the first conductive baseplate is coupled to the first housing such that the first conductivebase plate closes the opening at the second end of the first housingwith the first number of semiconductor switches disposed in the interiorof the first housing and the second surface of the first conductive baseplate is exposed to the exterior of the first housing to transfer heatfrom the first housing; at least a second switch module comprising: asecond housing of an electrically insulative material forming aninterior and an exterior, the interior of the second housing open to theexterior at a first end and at a second end; a second conductive membersupported by the second housing, the second conductive member comprisingan exterior portion extending from the second housing into the exteriorand a perimeter portion forming at least one shelf extending from thesecond housing into the interior of the second housing; a secondconductive base plate comprising a first surface and a second surfaceopposed to the first surface; a second insulating substrate carried bythe first surface of the second conductive base plate; a firstconductive pattern and a second conductive pattern carried by the secondinsulating substrate, the second insulating substrate electricallyinsulating the first and the second conductive patterns from the secondconductive base plate; and a second number of semiconductor switcheseach comprising a first active terminal, a second active terminal and acontrol terminal, the first active terminal of each of the second numberof semiconductor switches surface mounted to the first conductivepattern, a number of wire bonds electrically coupling the second activeterminal of each of the second number of semiconductor switches to thefirst surface of the second conductive base plate, and a number of wirebonds electrically coupling the control terminals of the second numberof semiconductor switches to the second conductive pattern, wherein thesecond conductive base plate is coupled to the second housing such thatthe second conductive base plate closes the opening at the second end ofthe second housing with the second number of semiconductor switchesdisposed in the interior of the second housing and the second surface ofthe second conductive base plate is exposed to the exterior of thesecond housing to transfer heat from the second housing; and a phaseterminal structure, wherein the first and the second conductive baseplates are electrically coupled to the phase terminal structure.
 10. Thepower converter of claim 9 wherein the second surfaces of the first andthe second conductive base plates are in direct physical contact withthe phase terminal structure over substantially the entire area of thesecond surfaces.
 11. The power converter of claim 10 wherein the phaseterminal structure comprises a metal bar with at least one pair ofopposed faces, and the first switch module is mounted to a first one ofthe pair of opposed faces and the second switch module is mounted to asecond one of the pair of opposed faces.
 12. The power converter ofclaim 11 wherein a distal portion of each of the exterior portions ofthe first and the second conductive members extends at an approximatelyright angle to the opposed faces of the pair of opposed faces.
 13. Thepower converter of claim 12 wherein the distal portion of each of theexterior portions of the first and the second conductive members isparallel to and spaced from a portion of the metal bar that extendsbetween the pair of opposed faces.
 14. The power converter of claim 11wherein a single phase of the power converter includes the first switchmodule, the second switch module, a third switch module and a fourthswitch module.
 15. The power converter of claim 9 wherein the firstsurface of the first conductive base plate is thermally coupled to thesecond surface of the first conductive base plate without an interveningthermally resistive material.
 16. The power converter of claim 9 whereinthe first conductive base plate consists of a plate of a metal.
 17. Thepower converter of claim 9, further comprising: a first set of signalterminals supported by the first housing, a portion of each of thesignal terminals of the first set of signal terminals extending from thefirst housing into the exterior and a portion of each of the signalterminals of the first set of signal terminals extending from the firsthousing into the interior of the first housing; and a first set of wirebonds electrically coupling the portion of the signal terminalsextending from the first housing into the interior of the housing withthe conductive pattern.
 18. The power converter of claim 17, furthercomprising: a second set of signal terminals supported by the secondhousing, a portion of each of the signal terminals of the second set ofsignal terminals extending from the second housing into the exterior anda portion of each of the signal terminals of the second set of signalterminals extending from the second housing into the interior of thesecond housing; and a second set of wire bonds electrically coupling theportion of the signal terminals extending from the second housing intothe interior of the second housing with the second conductive pattern.19. The power converter of claim 9 wherein the first insulatingsubstrate and the first conductive pattern comprise two layers of eithera direct bond copper substrate or a direct bond aluminum substrate. 20.The power converter of claim 9 wherein the first number of switchescomprises unpackaged bare silicon die transistors.